The use of one or more solenoids to control the locked and unlocked conditions in an electronic locking device is well known. It is preferable when forming such locks to use a solenoid with a pair of shuttles which act in opposing directions. This ensures that the locking device cannot be overcome by simply applying a strong magnetic field to one side of the lock to move the shuttle since the pair of shuttles must move in opposite directions to unlock the device and the magnetic field will act on them both in the same direction causing at least one to remain in its locked condition. With such bidirectional shuttles, the space required to easily operate makes it desirable to align the solenoid coaxially within the plug and cylinder. An example of such an electronic locking device is disclosed in our earlier application published by the European Patent Office under the number EP1331328. The operation of the solenoid in this device requires the cylinder to be constructed from a pair of cast components which together form the cylinder. However, to produce such a cast component economically requires materials other than stainless steel or brass to be used. Zinc Alloy, commonly known as Mazak or Zamak, is an example of these castable materials. The use of these other materials is generally undesirable as they lack the strength, wear resistance and other important properties of materials for locks. For these reasons, they are unpopular with locksmiths.
Lock snapping is a known vulnerability of some euro cylinder locks and similar devices. It is therefore commonplace for an intruder, when confronted with a euro cylinder to attempt a lock snapping attack. Many locks are formed with additional security measures to attempt prevent lock snapping allowing access to the internal working of the lock. However, many of these are not suitable for use with electronic locks leaving them vulnerable to a snapping attack.
Preferred embodiments of the present invention seek to overcome or alleviate the above described disadvantages of the prior art.